Transmission for a motor vehicle

ABSTRACT

A transmission for a motor vehicle with a drive motor (3) is arrayed transversely to the direction of motion with an automatic speed change transmission (1) flange-mounted coaxially, where between drive motor (3) and the speed change transmission (1) there is preferably provided a hydrodyanmic unit (2), e.g. a hydrodynamic torque converter (20), the transmission having an axle drive (4) which is driven via a countershaft (5) and constant pairs of spur gears (51, 52, 53, 54, 55). For the attainment of at least one further speed a shiftable partial transmission (6) is additionally arrayed coaxially with the axle drive (4) and connected thereto.

FIELD OF THE INVENTION

This invention concerns a transmission for a motor vehicle.

BACKGROUND OF THE INVENTION

For the attainment of the maximum possible available space in smallpassenger motor vehicles, the drive motors are arrayed transversely tothe direction of motion, and provided in connection with a front wheeldrive. This configuration just barely manages to accommodate the drivemotor and a multi-speed automatic transmission flanged thereonto, withthree or at most four speeds, depending on the torque to be transmitted.Unfortunately, the space transverse to the direction of motion underthis configuration is taken up to such an extent that at full steeringexcursion, and with snow chains installed, the chains already impinge onthe transmission so that a further increase of the number of speeds doesnot appear to be possible.

Such transmission is known from company publication F1/36 WH 816009(page 3) and also as represented in bulletin sheets F43/301/RT 3356-683and F 43/437 RT 3397-683. A similar disclosure is found in DE-OS No. 2919 167 and DE-OS No. 29 19 405.

For small passenger motor vehicles it is highly important to lower thefuel consumption by better adaptation of the drive train to the morefuel efficient portion of the drive motor performance curve.

It is therefore an objective of the invention to further develop atransmission for a motor vehicle by increasing the number of speeds withthe goal of adapting the drive train better to the drive motor, withouthaving to enlarge the available installation space. Achievement of thisobjective will mean cost savings in development and manufacture.

SUMMARY OF THE INVENTION

A transmission for a motor vehicle with a drive motor is disclosedwherein a first axis traverses a length of the motor, which length isarranged transversely to the direction of the vehicle motion, andcomprises:

an automatic transmission coaxial with the first axis,

a hydrodynamic torque converter positioned between the automatictransmission and the motor;

a countershaft arrayed on a second axis parallel to the first axis;

an axle drive mounted along a third axis parallel to the second axisactuated by the countershaft;

a first and second set of spur gears separated from one another andtransversely connected to the countershaft; and

a partial transmission communicating with the automatic transmission todeliver at least one more speed, the partial transmission being placedcoaxially along the third axis and connected to the axle drive.

If an automatic transmission as generally known, and arranged in knownmanner, is extended by a partial transmission which is arrangedcoaxially to the axle drive and is connected therewith, then at leastone additional speed can be gained with relatively simple means becauseno changes need to be made to the already existing transmission. A smallinstallation space parallel to the drive motor is already normallyavailable and may be utilized by the partial transmission. Use of thisspace will allow retention of the known arrangement of drive motor andspeed change transmission and even of the axle drive. Only the axledrive has to be adapted to the new partial transmission, which requiresrelatively little effort, considering the success achieved.

Where the partial transmission is applied as a simple planet gear setwith the clutches and brakes necessary for shifting, and with a freewheel unit, and the axle drive is implemented as a planet geardifferential, the combination of these two drives is possible in aparticularly simple manner. The transmission housing can be adaptedappropriately on one hand by an entirely new housing, or, on the otherhand, by means of extending the housing which in principle alreadyexists with a housing for the axle drive and the partial transmission.The particular option chosen will depend on the quantity oftransmissions to be fabricated.

By means of simple connections but driven differentially, between theaxle drive and the partial transmission, a five-speed transmission withone or two overdrives can be achieved in connection with a four-speedtransmission in the hitherto known arrangement. Thereby the usualcountershaft arrangement of the known four-speed transmission can beeliminated, which is of particular advantage.

BRIEF DESCRIPTION OF THE DRAWINGS

Further details of the invention are explained hereinafter through thedescription and drawings of various embodiments. The drawings includethe following figures:

FIG. 1 is a schematic representation of the drive axle connected withthe drive motor and transmission.

FIG. 2 is a transmission construction in schematic representation;

FIG. 3 is a schematic of clutches and brakes shifted depending on speedsaccording to FIG. 2;

FIG. 4 is a transmission construction according to FIG. 2, but in asecond embodiment; and

FIG. 5 is a schematic according to FIG. 3, but coordinated to FIG. 4.

DETAILED DESCRIPTION

In FIG. 1, the speed change transmission is designated by 1, ahydrodynamic torque converter by 2, and the drive motor by 3. Thepositive connection to the axle drive 4 occurs via spur gears 51, 52,the countershaft 5, and the spur gears 53 and 54. The partialtransmission 6, arrayed parallel to the drive motor 3, is connected tothe former axle drive 4. Drive wheels 7 are driven from axle drive 4 viathe drive shafts 71. The housing of the speed change transmission isdesignated 11, the housing section nearest the axle drive with 45, andthe housing section nearest the partial transmission with 65. Togethersections 45 and 65 form a common housing.

In the schematic drive arrangement of FIG. 2, a four-speed automatictransmission 10, known as such, is complemented in a known manner by ahydrodynamic torque converter 20. The countershaft 5 with the spur gearsets 51, 52 and 53, 54 serves as drive for a planetary differential,e.g. in a transversely mounted drive motor in a front wheel drivevehicle. Spur gear 54 is connected to ring gear 62 of a simple planetarygear set 60 and to a shift coupling F of the partial transmission 6. Sungear 61 has a solid connection to free-wheel unit III, which issupported in the housing, as well as with a brake G and additionallywith another friction element of clutch F. Arm 63 of the simple planetgear set 60 of partial transmission 6 is connected to the internal gear42 of the planetary differential 40, and the power output occurs on theone hand via sun gesar 41 of the output shaft 46, and on the other handvia arm 43 of the two meshing planets towards output shaft 47, where thetwo output shafts 46 and 47 are linked to the drive shafts 71 (FIG. 1)for the drive wheels 7. By means of the connection of the spur gear 54with the simple planet gear set 60 and the axle differential 40, thefour-speed main transmission is expanded into a five-speed transmissionwith three speeds into lower ranges, one direct-drive speed, and oneoverdrive. FIG. 3 calculates for a better understanding the relationshipof the engaged clutches and brakes and active free wheel units in thevarious speeds.

The drive schematic shown in FIG. 4 is in principle similar to FIG. 2,but here only the spur gear 55 of the second spur gear set 53/55 isconnected to arm 68 of the simple planet gear set, a free-wheel unitIII1 and the clutch F1. Sun gear 66 of the simple planet gear set 600 isdriveably connected to free-wheel unit III1, to clutch F1 and to brakeG1. The power output from partial transmission 6 to the planetarydifferential is delivered to ring gear 48 via ring gear 67, whereby thetwo ring gears can be made of a single piece. By means of this positivedrive connection, deviating from FIG. 2, between the spur gear 55, thesimple planet gear set 600 and the axle differential 400, two speeds areobtained into lower ranges, i.e. one direct drive and two overdrives.FIG. 5 shows, in a format according to FIG. 3, the engaged clutches andbrakes as well as the effective free-wheel units in the several speedsper the layout of FIG. 4.

Naturally in place of the four-speed transmission 10 in FIGS. 2 and 4,all other known and possible three- and four-speed transmissions can beprovided as main transmission 10, where in every case an additionalspeed is gained by means of partial transmission 6.

I claim:
 1. A transmission for a motor vehicle with a drive motorwherein a first axis traverses a length of said motor, which length isarranged perpendicular to the direction of the vehicle motion,comprising:an automatic transmission coaxial with said first axis; ahydrodynamic torque converter positioned between said automatictransmission and said motor; a countershaft arrayed on a second axisparallel to said first axis; an axle drive comprising a planetarydifferential mounted along a third axis parallel to said second axisactuated by said countershaft; a first and second set of spur gearsseparated from one another and transversely connected to saidcountershaft; a partial transmission comprising a simple planetary gearset communicating with said automatic transmission to deliver at leastone more speed, said partial transmission being placed coaxially alongsaid third axis and connected to said axle drive; and a further spurgear driven by the countershaft; a ring gear which is a part of saidsimple planetary gear set; a clutch; a sun gear; a brake; a free-wheelunit supported by a housing; a planet carrier and a planetary ring gearwhich is part of said differential; a first and second output shaft; apair of drive wheels; two meshing planets of said planetary differentialhaving a meshing sun gear and an arm; and wherein said automatictransmission has four speeds and that for the attainment of anadditional speed in said partial transmission said further spur gear isconnected with the ring gear of said single planetary gear set and withsaid clutch, the sun gear with said clutch, and said brake as well assaid free-wheel unit are supported by the housing and the planet carrierwith said ring gear of said differential and that said first and secondoutput shafts are connected to the drive wheels by means of said sungear and said arm of the two meshing planets and that thus there isobtained in addition to a reverse gear, altogether three speeds in thelow range, one direct drive and one overdrive.
 2. A transmissionaccording to claim 1 wherein said axle drive, partial transmission,hydrodynamic torque converter, and automatic transmission are emplacedwithin a common transmission housing.
 3. A transmission according toclaim 1 wherein the axle drive and the partial transmission are emplacedin a common housing, said housing have one or more flanges by which saidhousing is mounted onto said automatic transmission.
 4. A transmissionaccording to claim 1 wherein the partial transmission is emplaced in apartial housing, said partial housing having one or more flanges throughwhich the partial transmission is mounted onto a transmission housingcovering the automatic transmission, the hydrodynamic torque converter,and the countershaft.
 5. A transmission for a motor vehicle with a drivemotor wherein a first axis traverses a length of said motor, whichlength is arranged perpendicular to the direction of the vehicle motion,comprising:an automatic transmission coaxial with said first axis; ahydrodynamic torque converter positioned between said automatictransmission and said motor; a countershaft arrayed on a second axisparallel to said first axis; an axle drive comprising a planetarydifferential mounted along a third axis parallel to said second axisactuated by said countershaft; a first and second set of spur gearsseparated from one another and transversely connected to saidcountershaft; a partial transmission comprising a simple planetary gearset communicating with said automatic transmission to deliver at leastone more speed, said partial transmission being placed coaxially alongsaid third axis and connected to said axle drive; and a further spurgear driven by the countershaft; an arm and a first ring gear comprisinga part of said simple planetary gear set; a clutch; a free-wheel unit; asun gear; a brake; a second ring gear of said planetary differential; afirst and second output shaft; a pair of drive wheels; two meshingplanets of said planetary differential having a meshing sun gear and anarm; and wherein said automatic transmission has four-speeds and thatfor the attainment of an additional speed in said partial transmissionthere is located said further spur gear connected to said arm of saidsimple planetary gear set as well as to said clutch and said free-wheelunit, said sun gear being connected with said clutch, said free-wheelunit, and said brake, and that the first ring gear is connected with thesecond ring gear of the planetary differential, and that said two outputshafts are connected to said drive wheels via the sun gear and arm ofsaid two meshing planets of the planetary differential, and through thisarrangement obtaining in addition to a reverse gear, altogether twospeeds in the low range one direct speed and two overdrives.
 6. Atransmission according to claim 5 wherein said ring gears of the simpleplanetary gear set and the planetary differential are constructed as asingle piece.